Common faults and solutions for freeze dryers

Fault name

Common malfunctions

solution

Power on
Dryer does not work

Incoming line has no voltage or voltage is too low

Check incoming power switch, fuse
And troubleshoot

High voltage protection switch disconnected

Reset

Loose wiring

Check wiring and tighten

Compressor motor burnout

Inspection, replacement

AC contactor damage

Inspection, replacement

Refrigerant leakage

Check leaks, traps, add refrigerant

Automatic air switch is not turned on

Turn on the automatic air switch

compressor
Running break

Low voltage switch is not working properly

Check if the control line of the low-voltage switch is blocked, check the switch position

Insufficient refrigerant

Adding refrigerant

Inhalation valve closed or partially closed

turn on

Hot gas bypass valve blocked

repair

Expansion valve or capillary ice block

Replacement of refrigerant

Condensation pressure is too high

Ambient temperature is too high

Increase environmental ventilation

Fan switch setting is not normal

Adjust the set value

Wind condenser heat dissipation is not good

Blowing the condenser with dry compressed air

Insufficient cooling water

Increase the amount of cooling water

Too much refrigerant

Release too much refrigerant

Air in the refrigeration cycle

Vacuuming and replacing refrigerant

Water condenser heat dissipation

Clean the condenser with dilute hydrochloric acid and a brush

Condensation pressure is too low

Evaporation pressure is too high

Fan switch setting is not normal

Adjust the set value

Hot gas bypass valve opens too large

Counterclockwise adjustment of the bypass valve

The amount of cooling water is too large

Turn off small cooling water

Expansion valve opening is too large

Clockwise small expansion valve

The expansion valve temperature sensor package is not close to the evaporator outlet pipe wall

Reinstall the temperature sensor package

Expansion valve failure

Replace the expansion valve

Evaporation pressure is too low

Insufficient refrigerant

Adding refrigerant

System noise

Insufficient gap between compressor piston and valve plate

Replace damaged parts

Sound from the expansion valve

Add refrigerant, replace filter

The sound of the hot gas bypass valve

This sound is normal and does not affect the operation.

Export air
Excessive pressure drop

Handling air volume exceeds rated value

Optional dryer according to actual air volume

The piping system is unreasonable:
The pipe diameter is too small, the aisle length is too long, and there are too many turning elbows

Reset the piping system

Import and export valves are not fully open

Open the inlet and outlet valve

There is a leak in the pipe or the filter is clogged

Repair or dredge pipes and filters

The evaporator pipe is frosted and blocked.

Handling frost, dredging pipes

Poor dehumidification

Inlet pressure is too low
Ambient temperature is too high
Handling excessive air volume
Inlet temperature is too high

The working conditions should meet the requirements of the nameplate or re-select the dryer

Air bypass valve is not closed

Close the air bypass valve tightly

Automatic drainage system failure
Drain front stop valve is not open
The drain is clogged or damaged
Air pressure is less than 0.6MPa
Drain pipe is higher than drain

Open stop valve
Cleaning and replacing the drain
Air pressure must not be lower than 0.6MPa
Reinstall the drain

During operation
Unplanned downtime

The fuse is blown or controlled to open and jump off

Check the power supply voltage and control circuit,
Replace the fuse after removing the abnormality

Thermal relay open circuit

Check the voltage and current values, and reset the thermal relay after the compressor is abnormally removed.

Automatic air switch open circuit

After opening the way, open the air

High condensing pressure causes high voltage open circuit
Ambient temperature is too high
Inlet temperature is too high
Handling excessive air volume
Poor heat sink

Adjust the condition or re-select the dryer
Air-cooled; remove the surface ash of the wind condenser, keep the cooling air duct unobstructed
Water-cooled type; cleaning water condenser scale ensures water condenser heat transfer effect

Low evaporation pressure leads to open circuit of low voltage switch
The ambient temperature is too low and the load is too small
Insufficient opening or blockage of expansion valve
Refrigeration system drying filter blocked
Refrigerant leakage

Turn the hot gas bypass valve clockwise
Adjust or replace the expansion valve
Replace the dry filter
Check for leaks, traps, and re-add refrigerant

Electrical component damage

Replace damaged components after inspection